TWI412489B - Production of hydrogen from non-cyclic organic substances having multiple alcohol functionality - Google Patents

Abstract

A method of producing hydrogen gas from a reaction of an organic substance having multiple alcohol functionality with a base. Hydrogen can be produced in a reaction of a base with an organic substance having multiple alcohol functionality that may proceed through the formation of a bicarbonate or carbonate compound as a byproduct. In some embodiments, the reaction may occur in the presence of water. The preferred organic substances include diols, triols, and higher order alcohols. Non-cyclic (linear or branched) organic substances having multiple alcohol functionality are among the preferred reactants. The instant base-facilitated hydrogen-producing reactions are thermodynamically more spontaneous than the corresponding conventional reformation reactions of the organic substances and can produce hydrogen at less extreme reaction conditions. The preferred reactants further include low volatility organic substances having multiple alcohol functionality. Such reactants permit the efficient formation of hydrogen in a liquid phase system and enable a continuous reaction capability in the liquid phase without the need to condense volatilized reactant.

Description

Method for producing hydrogen from an acyclic organic substance having polyol functionality [Related application cross-reference]

The present application is filed on Jan. 23, 2004, and is hereby incorporated by reference in its entirety in its entirety, the entire disclosure of the entire disclosure of the entire disclosure of the entire disclosure of the entire disclosure of And the continuation of the application number No. 10/636,093, entitled "Recovery of Carbonate in Hydrogen Production", filed on August 7, 2003, and published as US Patent Publication No. US2004/0028603 A1. The disclosed persons are incorporated in the present application for reference.

The present invention relates to a process for producing hydrogen from organic materials. More particularly, the present invention relates to a process for producing hydrogen from low volatile alcohols. Most particularly, the present invention relates to a process for producing hydrogen via an organic material having two or more alcohol groups per molecule in the presence of a base.

Modern society relies heavily on the energy derived from fossil fuels to maintain its standard of living. With the modernization of more societies and the expansion of the current modern society, fossil fuel consumption continues to increase, and the global increase in dependence on the use of fossil fuels is causing many problems. First, fossil fuel systems are a limited resource, and things that are increasingly being taken care of for fossil fuels will be completely depleted in the foreseeable future. Rare problems increase the likelihood that gradually increasing costs may make the economy unstable, and the possibility that the country will fight with the remaining reserves. Second, fossil fuels are highly polluting. A greater amount of fossil fuel combustion can quickly incur global warming and the dangers of ecosystem stability. In addition to greenhouse gases, the burning of fossil fuels produces coal ash and other pollutants that are not harmful to humans and animals. In order to prevent the gradual increase in the harmful effects of fossil fuels, new energy sources must be available.

The required characteristics of a new fuel or energy source include low cost, adequate supply, recyclability, safety and environmental compatibility. Hydrogen is a promising candidate for providing these properties and provides a significant reduction in the potential for people to rely on traditional fossil fuels. Hydrogen is the most ubiquitous element in the universe, and if its potential is realized, it can provide an inexhaustible source of fuel to meet the world's increased energy needs. Hydrogen can be obtained from many sources, including coal, natural gas, hydrocarbons (universal), organic materials, inorganic hydrides, and water. These sources are geographically well distributed throughout the world and are available to most of the world's population without importation. In addition to being extensive and widely available, hydrogen is also a source of clean fuel. The combustion of hydrogen produces water as a by-product. Thus, the use of hydrogen as a fuel source avoids unwanted carbon and nitrogen-based greenhouse gases (which are responsible for global warming), as well as unwanted ash and other carbon-based contaminants in industrial processes.

Understanding the existence of hydrogen as a source of energy ultimately depends on its economic viability. An economically viable hydrogen production process and an efficient means of storing, transferring and consuming hydrogen are necessary. Chemical and electrochemical methods have been disclosed to produce hydrogen. The most readily available hydrogen feedstocks are organic compounds, primarily hydrocarbons and oxygenated hydrocarbons. Common methods for producing hydrogen from hydrocarbons and oxygenated hydrocarbons are dehydrogenation reactions and oxidation reactions.

Steam reforming reactions and electrochemical hydrogen production from water via electrolysis are two common strategies currently used to produce hydrogen. However, both strategies suffer from the disadvantage of limiting their practical application and/or cost effectiveness. The steam reforming reaction is endothermic at room temperature and typically requires several hundred degrees of temperature to achieve an acceptable reaction rate. These temperatures are costly to provide, impose special requirements on the materials used to construct the reactor, and limit the scope of application. The steam reforming reaction also occurs in the gas phase, which means that hydrogen must be recovered from the gas mixture via the separation procedure, thus adding cost and complexity to the reforming process. The steam reforming reaction also causes unwanted greenhouse gases, CO ₂ and/or CO, to be produced as by-products. Water electrolysis has not been widely used in practice because of the high electrical energy cost required for electrolysis of water. The water electrolysis reaction requires a high minimum voltage to initiate even higher voltages to achieve an enforceable hydrogen production rate. High voltages result in high electrical energy costs (in terms of water electrolysis reactions) and inhibit their widespread use.

In U.S. Patent No. 6,607,707 (the ' 707 patent), the disclosure of which is incorporated herein by reference in its entirety in its entirety in the the the the the the the the the the the the Classes produce hydrogen. Using thermodynamic analysis, the inventors of the present invention confirmed that many hydrocarbons and oxygenated hydrocarbons react spontaneously with a base or alkaline aqueous solution under special reaction conditions to form hydrogen, while the same hydrocarbons and oxygenated hydrocarbons Under the same reaction conditions, it is not spontaneously reacted in a conventional steam reforming procedure. Therefore, the inclusion of a base system has been shown to promote the formation of hydrogen from a plurality of hydrocarbons and oxygen-containing hydrocarbons, and to enable the production of hydrogen gas under conditions which are less severe than those typically encountered in steam reforming reactions, thereby improving the production of hydrogen. Cost-effective. In many reactions, the process of the '707 patent results in the formation of hydrogen from the liquid phase reaction mixture (in some instances, at room temperature), where hydrogen is the only gaseous product and thus can be readily recovered without the need for a gas phase. Separation step. '707 patent further reaction operate via the carbonate ion form or bicarbonate ion and avoid the generation of greenhouse gases CO and CO _2. The inclusion of a base system produces a new reaction pathway for the formation of hydrogen, with the thermodynamic advantage of allowing hydrogen to be produced at a lower temperature than would be required for the corresponding steam reforming procedure.

In U.S. Patent No. 6,890,419 (the '419 patent), the disclosure of which is incorporated herein by reference in its entirety in its entirety in the the the the the the the the the the , hydrogen is produced from organic substances. It shows that the electrochemical reaction of organic matter with water to produce hydrogen requires a lower electrochemical cell voltage than water electrolysis. It also shows that the electrochemical reaction of organic materials in the presence of acids or bases requires low electrochemical cell voltages at room temperature.

In the co-pending U.S. Patent Application Serial No. 10/636,093, the entire disclosure of which is hereby incorporated by reference in its entirety in the entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire content The realization of the beneficial properties of the reactions disclosed in the '707 patent and the co-pending '419 application requires a systematic consideration of the cost and overall efficiency of the reaction. In addition to energy input and raw materials, consideration must be given to the handling or utilization of by-products. The most important consideration is the management of the carbonate and bicarbonate ion products of the disclosed hydrogen production reaction. In the co-pending '093 application, the inventors of the present invention disclosed strategies for recovering carbonate and bicarbonate ions. The carbonate recovery procedure is described as comprising a first step in which carbonate ions are reacted with a metal hydroxide to form a soluble metal hydroxide and a weakly soluble or insoluble carbonate. The soluble metal hydroxide can be returned to the hydrogen production reaction as a base reactant for further hydrogen production. In the second step, the carbonate is thermally decomposed to produce metal oxides and carbon dioxide. In the third step, the metal oxide is reacted with water to reform the metal hydroxide used in the first step. Thus, with respect to metal hydroxides, the carbonate recovery procedure is maintainable, and with regard to the bases, the total hydrogen production process is maintained via the carbonate recovery procedure of the '093 application. Similarly, according to the '093 application, the bicarbonate by-product of the reaction of the organic substance with the hydrogen production of the base can be recovered by first converting the bicarbonate by-product to carbonate, followed by recovery of the bicarbonate.

U.S. Patent Application Ser. In the '001 application, the disclosures are incorporated herein by reference in its entirety by reference in its entirety in its entirety in the the the the the the the the the Of particular importance in the 616 application is the manufacture of hydrogen from petroleum-related or petroleum-derived starting materials such as long-chain hydrocarbons; fuels such as gasoline, kerosene, diesel, petroleum distillates and their constituents; and mixtures of organic materials. . The '001 application considers the production of hydrogen from biomass and naturally occurring organic matter. In the U.S. Patent Application Serial No. 10/984,202, the disclosure of which is incorporated herein by reference in its entirety in its entirety in the the the the the the the the the the

The hydrogen production reactions of the above patents and applications provide an efficient, environmentally friendly method to produce the hydrogen needed to upgrade the basic economy of hydrogen. It is necessary to further expand the family applicability range in which the base promotes the reaction hydrogen production reaction. Of particular interest is the range of starting materials available for use in the reaction and the identification of starting materials for use in continuous reaction procedures.

Summary of invention

The present invention provides a process for the production of hydrogen from a chemical or electrochemical reaction of a low volatile organic material with a base. Preferred low volatility organic materials are those having two or more alcohol groups per molecule, including glycols, triols and higher alcohols. Specific examples include ethylene glycol and glycerin.

The method of the present invention comprises the step of reacting an organic substance having a polyol function with a base to produce hydrogen. The reaction can be carried out chemically or electrochemically. The alkali-promoted hydrogen production reaction of the present invention improves the thermodynamic spontaneity of hydrogen production from organic substances having polyol functionality relative to the method of producing hydrogen by a corresponding conventional reforming method. In a specific example, the greater thermodynamic spontaneity is allowed to be promoted by the base at a lower temperature than that required in the conventional reforming reaction for producing hydrogen from an organic substance. Hydrogen production produces hydrogen. In another embodiment, the greater thermodynamic spontaneity allows the base to promote the reaction at a particular temperature, at a rate that is faster than the conventional reforming reaction of the organic material at a particular temperature, by having a polyol function. Organic matter produces hydrogen.

In one embodiment, the organic material having polyol functionality is reacted with a base to form a carbonate or bicarbonate compound as a by-product. In another embodiment, the organic material having polyol functionality is reacted with a base to form a salt (precipitated or dissolved) of the organic material in oxidized form.

In one embodiment, the base-promoted hydrogen production reaction is carried out in a solution or liquid phase using a low volatility organic substance having a polyol function. In this embodiment, the reaction rate of the organic substance in the liquid phase below its boiling point is sufficiently large, so that efficient hydrogen production is allowed, and the raw material is not significantly lost due to the volatilization. The need to condense the feed vapor is thus eliminated, thereby allowing for continuous operation of the reaction.

Detailed description of the invention

The present invention is related to, for example, U.S. Patent No. 6,607,707 (the '707 patent), U.S. Patent Application Serial No. 6,890,419 (the '419 patent), U.S. Patent Application Serial No. 10/763,616 (the '616 application), and U.S. Patent Application Serial No. The chemical and electrochemical hydrogen production reactions of those disclosed in No. 10/966,001 (the '001 application) are incorporated herein by reference. In particular, the present invention provides a process for the manufacture of hydrogen from organic materials having polyol functionality and mixtures thereof.

In one embodiment, the hydrogen is produced in a base-promoted reaction from a low volatility organic material having a polyol functionality, which is carried out via the formation of a carbonate or bicarbonate by-product compound. The carbonate or bicarbonate by-product may comprise a carbonate or bicarbonate ion as a product in a liquid phase solution and may comprise a solid phase carbonate or bicarbonate.

In another embodiment, the hydrogen is produced in a base-promoted reaction from a low volatility polyol-functional organic material that is a by-product via a salt that forms an oxidized form of the organic material (eg, The organic acid salt) is carried out. The organic salt by-product can remain dissolved in the liquid phase and can precipitate.

In the present invention, an organic substance having a polyol function is used as a raw material or a starting material in a base-promoted hydrogen production reaction. As discussed in the '707 patent, the '419 patent, the '616 application, and the '001 application, the reaction of organic materials with bases under specific conditions allows for the formation of carbonate ions and/or bicarbonate by-products. hydrogen. The method for producing hydrogen from an organic substance includes a reaction in which a base is a reactant and thus provides a reaction with respect to a conventional organic matter reforming reaction (through a route leading to production of CO ₂ by reaction of an organic substance with water) path.

Under the specific reaction conditions of the group, the selective reaction reaction of the alkali-promoted organic matter reforming reaction in the present case leads to more spontaneous (or less non-spontaneous) )reaction. For purposes of illustration, comparative examples of oxidized hydrocarbons from the '707 patent can be considered. The process for producing hydrogen from ethanol can be carried out by the following reaction (1), (2) or (3) (in a standard liquid phase):

Reaction (1) is a conventional ethanol reforming reaction, and reactions (2) and (3) are alkali-promoted reforming reactions according to the '707 patent. In reactions (2) and (3), the hydroxide ion (OH ^- ) reactant is provided by a base. Reactions (2) and (3) differ in the relative amounts of hydroxide ions and ethanol. Reaction (2) contains lower levels of bases and is carried out by bicarbonate ion (HCO ₃ ^- ) by-products, while reaction (3) contains higher levels of bases and is transmitted through carbonate ions (CO ₃ ^- ) By-products are carried out.

ΔG ⁰ _{r x n} is the Gibbs free energy for each reaction under standard conditions (25 ° C, 1 atmosphere and unit active reactants and products). Gibbs free energy is an indicator of the thermodynamic spontaneity of chemical reactions. The spontaneous response has a negative Gibbs free energy, while the non-spontaneous response has a positive Gibbs free energy. Reaction conditions (eg, reaction temperature, reaction pressure, concentration, etc.) may affect the value of Gibbs free energy. A reaction that is non-spontaneous under one set of conditions may become spontaneous under another set of conditions. The number of Gibbs free energy is an indicator of the degree of spontaneity of the response. Gibbs free energy has more negative values (or less positive values), and the reaction is more spontaneous.

The above reforming reaction (1) is non-spontaneous under standard conditions. The base-promoted reforming reaction (2) is also non-spontaneous, but more spontaneous than reaction (1) (and will most likely become spontaneous at lower temperatures than reaction (1)). The method for producing hydrogen from the conventional ethanol reforming reaction (1) is more non-spontaneous in the alkali-promoted reaction, and includes a base to produce a reaction path for producing hydrogen from ethanol. Further addition of the base causes the Gibbs free energy to be further reduced, and finally provides a spontaneous reaction under the standard conditions exemplified in the above reaction (3). The ability of alkalis to improve the thermodynamic spontaneity of the process for producing hydrogen from organic materials is an important advantageous feature of the hydrogen production reaction of the present invention. Larger thermodynamic spontaneity allows for the spontaneous production of hydrogen from organic materials in a base-promoted reforming reaction under a specific set of reaction conditions, wherein conventional reforming reactions under the same conditions are non-spontaneous, thus It is not possible to produce hydrogen spontaneously.

The present invention is generally directed to a process for producing hydrogen from organic materials in a base-promoted reforming reaction. More particularly, the present invention demonstrates the feasibility of using alkalis to improve the thermodynamic spontaneity of hydrogen produced from selected organic materials. Of particular interest to the inventors is a process for the production of hydrogen from organic materials having polyol functionality. Acyclic organic materials having polyol functionality are preferred reactants in the base-promoted hydrogen production reaction of the present invention. Representative preferred embodiments include linear or branched diols, triols, and higher alcohols.

Hydrogen can be produced from a preferred organic material by a reforming reaction such as the above reaction (1). For one embodiment, hydrogen can be produced from ethylene glycol (C ₂ H ₆ O ₂ ), a diol in which each molecule contains two alcohol groups, in the following reaction (4):

The thermodynamic analysis of the reaction shows that under standard conditions, ΔG ⁰ _{r x n} = 2.0 kcal/mole and ΔH ⁰ _{r x n} = 57.4 kcal/mole, where ΔG ⁰ _{r x n} is Gibb Free energy, and ΔH ⁰ _{r x n} is the reaction enthalpy. Analysis showed that the reaction was slightly non-spontaneous under standard conditions. The reaction is also highly endothermic under standard conditions and requires a large amount of energy input for the reaction. In practice, the reforming reaction of ethylene glycol according to reaction (4) will require high temperatures and the hydrazine will proceed at a reasonable rate.

The thermodynamic analysis of the reaction (4) is a representative reforming reaction of an organic substance, and is similar to the reaction used in the reforming reaction (reaction (1)) of a simple compound such as methanol or ethanol. In practice, the need to operate at elevated temperatures to achieve an acceptable reaction rate represents high volatility compounds (e.g., methanol and ethanol) which are volatilized and reacted in a vapor phase in a conventional reforming reaction (e.g., reaction (1)).

Vapor phase reactions are undesirable in many applications because the reaction system requires a large volume. The liquid phase reaction is desirable when compaction is desired in the application since the liquid phase reaction can generally be carried out in a smaller reaction system. With the growing interest in using hydrogen as a fuel source, it is desirable to develop reactions and systems for the production of hydrogen in the liquid phase. The liquid phase reaction can be accomplished, for example, in a compact reactor (e.g., an on-board reactor) or in a micro or micro-sized fuel cell, providing a dense or portable hydrogen fuel production system for consumer applications.

It is not easy to react a volatile substance such as methanol or ethanol in the liquid phase because it has a tendency to volatilize. In order to maintain the liquid phase reaction, it is necessary to include a unit for condensing the volatile reactants (starting material, fuel) to prevent material loss. The coagulation unit must condense the vapor into a liquid phase and return the liquefied reactant to the reaction vessel to efficiently produce hydrogen from the volatile starting material in the liquid phase reaction. The need for a condenser increases the cost, volume, and weight of the reaction system, and this outperforms the goal of completing a hydrogen production reaction in a compact reaction system.

Low VOCs are more suitable for liquid phase reactions and can be used as more efficient reactants, starting materials or fuels in liquid phase reactions for hydrogen production. Low VOCs are more likely to remain in the liquid phase and eliminate the need for coagulation units, thereby facilitating the manufacture of hydrogen in a compact reaction system in a continuous manner. In order to realize a method for producing hydrogen from a low-volatile organic substance in a liquid phase, it is necessary to confirm a sufficiently reactive substance and a sufficiently usable reaction at a temperature which does not cause thermal decomposition of the reactant.

The more suitable thermodynamic properties of the reaction in this case allow for the formation of hydrogen from low volatility organic species at a significant rate in the liquid phase system, as well as reducing the temperature required for practical operation. Under the theory of the present invention, hydrogen is produced from organic materials having polyol functionality. Polyol functionality may be present when the organic material has two or more alcohol groups per molecule. Alcohol groups are polar and have a tendency to exhibit some degree of hydrogen bonding as well as electrostatic or van der Waals interactions, and these properties have the potential to increase the intermolecular interaction between molecules. By including two or more alcohol groups per molecule, the strength of the interaction between molecules is increased, and this increase has a tendency to cause a decrease in the volatility of the substance, thereby making the substance more suitable for liquid phase reaction.

In the present invention, an organic substance having a polyol function is reacted with a base such as sodium hydroxide (NaOH). Depending on the relative fraction of the base to be used, in one embodiment, hydrogen can be produced from an organic substance having a polyol function by a reaction of producing a carbonate or a hydrogencarbonate of a cation existing in a base.

The reaction system represented by ethylene glycol and sodium hydroxide formed by the formation of sodium carbonate (Na ₂ CO ₃ ) and sodium hydrogencarbonate (NaHCO ₃ ) is separately provided in the following reactions (5) and (6):

Thermodynamic analysis of reaction (5) showed that under standard conditions, ΔG ⁰ _{r X n} = -24.7 kcal/mole and ΔH ⁰ _{r x n} = 4.06 kcal/mole. Analysis shows that compared to the reforming reaction of ethylene glycol (4), the free energy and the enthalpy of causing the reaction in the hydrogen production reaction of the alkali are reduced under standard conditions. The base-promoted hydrogen production reaction (5) is spontaneous under standard conditions, but is non-spontaneous in the example of reforming reaction (4). Reaction (5) is also significantly less endothermic than reaction (4). Therefore, the alkali-promoted reaction (5) can theoretically be carried out in the liquid phase under milder conditions than the conventional ethylene glycol reforming reaction (4).

Thermodynamic analysis of reaction (6) showed that under standard conditions, ΔG ⁰ _{r x n} = -15.3 kcal/mole and ΔH ⁰ _{r x n} = 23.7 kcal/mole. The analysis shows that compared with the reforming reaction (4), the free energy and the enthalpy which cause the reaction in the hydrogen production reaction are reduced under standard conditions. The alkali-promoted hydrogen production reaction (6) The specific gravity reaction (4) is more spontaneous, but less spontaneous than the alkali-promoted reaction (5). The alkali-promoted hydrogen production reaction (6) maintains endothermic, but the specific gravity reaction (4) is less endothermic. Since the alkali-promoted reaction (6) specific gravity reaction (4) is less endothermic, the energy input required to operate the reaction (6) is smaller than that required for the reaction (4). Therefore, the temperature required to operate the reaction (6) at a practical rate in the liquid phase is expected to be much lower than the temperature required for the performance of the reforming reaction (4). The base-promoted reaction (6) thus provides a cost advantage over the reforming reaction (4) because less extreme conditions enable the hydrogen to be produced from the reaction (6) at a reasonable rate.

In the case of hydrogen production from another organic material having polyol functionality, the inventors have considered glycerol as the starting material in the base-promoted reaction. Glycerol is a triol having the formula C ₃ H ₈ O ₃ and has three alcohol groups per molecule. Hydrogen can be produced from glycerin in a reforming reaction as shown in the following reaction (7):

Thermodynamic analysis of the reaction showed that under standard conditions, ΔG ⁰ _{r x n} = 1.15 kcal/mole and ΔH ⁰ _{r x n} = 82.7 kcal/mole, where ΔG ⁰ _{r x n} is reactive Gibbs free energy, and ΔH ⁰ _{r x n} is the reaction enthalpy. Analysis showed that the reaction was non-spontaneous under standard conditions and was highly endothermic. The reaction thus requires a large amount of energy input for carrying out the reaction. The high energy input required for the glycerol reforming reaction according to reaction (7) will require high operating temperatures, 俾 at a reasonable rate, and may be impractical due to the thermal decomposition of glycerol.

In the theory of the present invention, hydrogen is produced from glycerol by reacting glycerol with a base such as sodium hydroxide (NaOH). Depending on the relative fraction of the base to be used, in one embodiment, hydrogen can be produced by a reaction of a carbonate or a hydrogencarbonate which produces a cation present in a base. The reaction system represented by glycerol and sodium hydroxide formed by the formation of sodium carbonate (Na ₂ CO ₃ ) and sodium hydrogencarbonate (NaHCO ₃ ) is separately provided in the following reactions (8) and (9):

Thermodynamic analysis of reaction (8) showed that under standard conditions, ΔG ⁰ _{r x n} = -38.9 kcal/mole and ΔH ⁰ _{r x n} = 2.6 kcal/mole. Analysis shows that, compared to the reforming reaction (7), the free energy and the enthalpy of causing the reaction in the hydrogen production reaction are reduced under standard conditions. The alkali-promoted hydrogen production reaction (8) is spontaneous under standard conditions and has become a far specific gravity reaction (7) and is less endothermic. Therefore, the alkali-promoted reaction (8) can theoretically be carried out under standard conditions in a liquid phase at a much more favorable condition than the conventional reforming reaction (7).

Thermodynamic analysis of reaction (9) showed that under standard conditions, ΔG ⁰ _{r x n} = -23.72 kcal/mole and ΔH ⁰ _{r x n} = 32.2 kcal/mole. Analysis shows that, compared to the reforming reaction (7), the free energy and the enthalpy of causing the reaction in the hydrogen production reaction are reduced under standard conditions. Alkali-promoted hydrogen production reaction (9) Specific gravity reaction (7) is more spontaneous, but less spontaneous than the alkali-promoted reaction (8). The alkali-promoted hydrogen production reaction (9) maintains endothermic, but the specific gravity reaction (7) is less endothermic. Since the alkali-promoted reaction (9) specific gravity reaction (7) is less endothermic, the energy input required for the reaction (9) is smaller than that required for the reaction (7). Therefore, the temperature required to operate the reaction (9) in the actual reactor is expected to be several hundred degrees lower than that required for the actual performance of the reforming reaction (7). The base-promoted reaction 9) thus provides a cost advantage over the reforming reaction (7) because less extreme conditions enable hydrogen to be produced from the reaction (9) at a reasonable rate.

The above-described specific examples of the alkali-promoted reaction in the present case are representative reactions of the bases in the liquid phase according to the present invention. The invention further encompasses specific examples in which the solid or molten phase is used in the present invention, as well as solid or molten phase carbonate or bicarbonate by-products, together with hydrogen. For example, a solid phase base (such as a solid phase or a crystalline phase sodium hydroxide) can be contacted with a liquid phase organic material having a polyol function, and the rhodium is subjected to a reaction for producing hydrogen. A representative example of this reaction is provided below:

In this reaction, ethylene glycol is reacted with solid phase sodium hydroxide to form solid phase sodium carbonate and hydrogen. The reaction occurs when solid phase sodium hydroxide reacts with liquid phase ethylene glycol. The reaction is carried out by solid phase sodium hydroxide without dissolving sodium hydroxide in ethylene glycol. In practice, the reaction can be carried out by a combination of soluble and insoluble sodium hydroxide. Thermodynamic analysis of reaction (10) showed that under standard conditions, ΔG ⁰ _{r x n} = -59.3 kcal/mole and ΔH ⁰ _{r x n} = -24.9 dry card/mole. The reaction (10) is both spontaneous and exothermic under standard conditions and is therefore a highly advantageous reaction. A similar reaction occurs when the vapor phase ethylene glycol reacts with the solid phase sodium hydroxide to form solid phase sodium carbonate and hydrogen. In a reaction further comprising water as a reactant, the water may be in the form of water vapor, liquid water or ice. The invention further comprises a starting material mixture of organic materials as starting materials, wherein at least one component of the mixture is an organic material having polyol functionality.

The inventors of the present invention have noted that the true ratio of base to organic material starting material is not limited by the stoichiometric ratios described in the representative reactions shown above. The process for the manufacture of hydrogen according to the present invention occurs with respect to any ratio of base and/or water to the organic starting materials and can be carried out by a combination of different reactions at a given set of reaction conditions and reactant levels. Hydrogen can be produced via the present invention along with the manufacture of carbonate by-products, bicarbonate by-products, or a combination of carbonate and bicarbonate by-products.

The present invention generally relates to the reaction of organic materials having polyol functionality with bases to form hydrogen. Preferred organic materials include acyclic organic materials (eg, ethylene glycol, glycerol) having polyol functionality, and extend to glycols, triols and higher alcohols, and acyclic organic materials (linear or Branched chain). As described above, in one embodiment, the carbonate and/or bicarbonate compound is formed as a by-product.

The present invention further comprises the hydrogen production reaction of an organic substance having a polyol function in the present case with a base, which is formed by other by-products, for example, in the following exemplary reactions (11) and (12) of ethylene glycol and glycerol, respectively. Alkoxide of matter, Or a salt of an organic substance in an oxidized form in the reaction of ethylene glycol with sodium hydroxide (for example, a salt of an organic substance in the form of a carboxylic acid or an aldehyde): The product Na ₂ C ₂ O ₄ is the disodium salt of oxalic acid. The thermodynamic analysis of reaction (13) shows that under standard conditions, ΔG ⁰ _{r x n} = -8.7 kcal/mole and ΔH ⁰ _{r x n} = 21.1 kcal/mole, so the reaction is under standard conditions. Spontaneous and slightly endothermic. In reaction (13), the two alcohol groups have been converted to the corresponding organic acid groups in the deprotonated form. A similar reaction produces hydrogen from other organic materials with polyol functionality. In this type of reaction, one or more alcohol groups of the organic material are oxidized to the aldehyde or acid form. Depending on the reaction conditions, the reaction product may be a carbonate, a hydrogencarbonate, an alkoxide, an aldehyde or a salt of a carboxylic acid or a composition thereof.

Example 1

This example demonstrates a process for producing hydrogen from the reaction of ethylene glycol with sodium hydroxide. A stainless steel reaction vessel having a volume of ~75 ml and a pressure transducer was used in this test. Sodium hydroxide (15 grams) and ethylene glycol (26 milliliters (28.6 grams)) were placed in the reactor. The relative amount of sodium hydroxide and ethylene glycol makes sodium hydroxide a limiting reactant. Water (2 ml) and Raney nickel catalyst (3.5 g) were also added. The reactor was purged by filling helium in the headspace of the reactor and five cycles of evacuation and recombination. The reactor was then filled with helium to a pressure of 1 atmosphere and sealed for testing.

In this test, the reactor was heated to several different temperatures and the rate of pressure increase was measured at each temperature. The temperature used is between 50 ° C and 110 ° C. The results are summarized as follows:

The gas produced via this reaction was collected and analyzed using gas chromatography. The gas is determined to consist essentially of pure hydrogen.

This example shows that hydrogen can be produced by the reaction of ethylene glycol with sodium hydroxide, the reaction requires a temperature of not more than 50 ° C, and hydrogen is the main gas phase product of the reaction.

Example 2

In this embodiment, hydrogen is produced by the reaction of ethylene glycol and sodium hydroxide in a fixed temperature reaction. The reactor described in Example 1 above was used in this test. Sodium hydroxide (7.5 g), ethylene glycol (14 g) and Raney nickel catalyst (1.75 g) were placed in the reactor. As described in Example 1, sodium hydroxide is the limiting reactant. . The reactor was flushed five times by filling and evacuating helium as in Example 1, loaded with helium to a pressure of 1 atmosphere, and sealed for testing. The reaction was heated to 110 ° C and the pressure in the reactor was measured as a function of time. As shown in Example 1, hydrogen is the main gas product of the reaction. The rate and amount of hydrogen produced by the reaction is measured as a function of reaction time. Some results are summarized in Figure 1, where the cumulative volume of hydrogen is reported in units of standard cubic centimeters. The hydrogen production rate was ~800 cubic centimeters per hour at the beginning of the reaction and decreased as the reaction proceeded (reactant consumption). At the end of the reaction, it is estimated that the reaction has reached a completion rate of ~50%. About 3,000 cubic centimeters of hydrogen has been produced at this time.

This example shows that it can be prepared by the reaction of sodium hydroxide with ethylene glycol in the absence of water.

Example 3

In this example, the hydrogen production rate formed by the reaction of sodium hydroxide with ethylene glycol was measured in an open system reactor (at 110 ° C) and analyzed for solid phase products. The reactor, reactants (including content) and conditions in Example 2 were used in this test except that the reactor was not sealed. Instead, the outlet of the reactor has a check valve to allow the gas phase product formed in the reaction to escape. A check valve is set to allow gas to flow out of the reactor when the pressure in the reactor reaches 50 psi. The gas system that escapes through the check valve is guided by the tube and collected in the inverse vector tube filled with water. When heated to 110 ° C, the rate of hydrogen produced (expressed in standard cubic centimeters per hour) and the cumulative volume of hydrogen produced are measured as a function of reaction time and the amount of water displaced in the cylinder is Benchmarked.

For this test, the cumulative volume of hydrogen produced (as a function of reaction time) is shown in Figure 2. The initial rate of hydrogen production was ~700 cubic centimeters per hour, and its system was observed to decrease continuously as the reaction neared completion. Based on the hydrogen content produced, it was determined that the reaction was substantially completed in the period of monitoring. At the end of this period, ~6800 cubic centimeters of hydrogen had been produced. The fact that the reaction is complete is evident because it shows: (1) a lack of undesirable side reactions that consume ethylene glycol (not produced hydrogen); and (2) all ethylene glycols that react by evaporation (slight or no) Ethylene glycol loss).

When the reaction is complete, the solid phase product formed during the reaction is collected and analyzed. X-ray analysis showed that the solid phase product included both sodium carbonate and sodium oxalate. The gas phase product was also analyzed and shown to contain substantially pure hydrogen.

This test shows that ethylene glycol is a suitable starting material for the production of hydrogen in a liquid phase reaction without the need to provide a condenser in the reactor, and the vaporized starting material is collected. This advantage can be achieved due to the low volatility of ethylene glycol and its sufficient reaction rate at temperatures well below the boiling point. Compared to other organic substances (such as ethanol or methanol) that form hydrogen at an acceptable rate only at or near the boiling point, the acyclic organic material having polyol functionality of the present invention exhibits a low evaporation tendency. Reacts efficiently at the temperature. Accordingly, the present invention provides a hydrogen production reaction that can be achieved in a continuous manner in a compact reactor such as a mini fuel cell or a micro fuel cell.

The above examples are illustrative of the invention. The present invention generally comprises the reaction of an organic material with a base to produce hydrogen wherein a solid phase by-product is formed. Preferred organic materials are acyclic (e.g., linear or branched) organic materials having two or more alcohol groups per molecule, and may also be referred to as organic materials having polyol functionality. Particularly preferred are acyclic organic substances which have a polyol function which can react with a base at a temperature at which the evaporation rate of the organic substance is not significant in the liquid phase reaction. The present invention can be accomplished by contacting a base with an organic substance either directly or in the presence of water.

The metal hydroxide is the preferred base in the present invention. Representative metal hydroxides include alkali metal hydroxides (eg, NaOH, KOH, etc.), alkaline earth metal hydroxides (eg, Ca(OH) ₂ , Mg(OH) _{2 ,} etc.), transition metal hydroxides, and Transition metal hydroxide and olefin hydroxide. Non-metal hydroxides such as ammonium hydroxide can also be used. Most of the hydroxides are solid under standard conditions. As described above, a base in the form of a solid, a liquid, a dissolved, a solvated or a solution can be introduced as a reactant in the hydrogen production reaction in which the base promotes the reaction in the present case. The aqueous solution is in the form of a preferred solution of the hydroxide. A solution comprising a polyol-functional organic material is in the form of a preferred solution of another hydroxide compound comprising a hydroxide compound in a dissolved or partially dissolved state. Suitable metal hydroxide bases include those which are purified or impure and which contain absorbed or hydrated water.

In addition to the production of hydrogen, the reaction in this case also produces by-products of carbonates, bicarbonates and/or organic salts (salts of organic reactants in oxidized form). One or more distinguishable by-products can be formed. By-products can be prepared in the form of a precipitate or in the form of a fully or partially soluble salt.

In another preferred embodiment of the invention, the present invention is carried out electrochemically with a base-promoting reaction system, and hydrogen is produced from an organic material having polyol functionality. As described in the '419 application, the electrochemical reaction required to reduce the hydrogen production by the substance in the hydrogen production reaction is reduced compared to the corresponding electrochemical reaction in the absence of a base. Potential (voltage). The invention further comprises applying an electrochemical reaction according to the parent application '419 application to the manufacture of hydrogen from an organic material having polyol functionality. In these specific examples, the organic materials and bases can be combined to form an aqueous or other electrolyte solution and placed in an electrochemical cell having an anode and a cathode. A voltage is applied between the anode and the cathode, and hydrogen is produced by electrolysis from an organic substance in the presence of a base in an electrochemical reaction according to the parent application '419. In a representative embodiment, the organic material is dissolved in an electrolyte, such as an aqueous electrolyte, which combines solids, liquids, or dissolved bases in an electrochemical cell to form an electrochemical system. The anode and cathode are placed in contact with the electrochemical system and electrochemically reacted to produce hydrogen via application of a voltage or by an electrical current between the anode and the cathode.

In yet another embodiment of the invention, the present invention is carried out in a base-promoting reaction system in combination with a carbonate or bicarbonate recovery reaction (discussed in the co-pending parent application '093 application). The carbonate or bicarbonate recovery reaction is intended to improve the overall efficiency of the hydrogen production reaction to form carbonate and bicarbonate by-products. A carbonate or bicarbonate compound is a by-product that must be sold, utilized, discarded or omitted as a commodity. In order to improve hydrogen production efficiency, carbonate or bicarbonate compound by-products must be recovered or utilized.

The '093 application discussion can be used to recover the recovery reaction of carbonate or bicarbonate by-products. Depending on the form of the carbonate or bicarbonate by-product formed in the base-promoting reaction, different reactions are discussed. In one embodiment, if the carbonate by-product forms a metal carbonate precipitate, the precipitate can be collected and thermally decomposed to obtain a metal oxide. This metal oxide can then be reacted with water to form a metal hydroxide which can be returned to the present case as a base to promote the reaction as a base reactant or, for example, with Ca(OH) ₂ to produce NaOH and CaCO ₃ . In another embodiment, if the carbonate by-product forms a metal carbonate that is soluble in the reaction mixture, it can be further reacted with a metal hydroxide, wherein the metal hydroxide is selected such that its metal carbonate Has a low solubility (low K _{s p} ), which in turn causes a displacement reaction to occur to precipitate a metal carbonate while leaving a soluble metal hydroxide (which can be used as a base reactant in a base-promoted reaction in the further operation of the present invention) . Likewise, bicarbonate by-products can be reused. Thus, the process for producing hydrogen via a base-promoted reforming reaction may optionally include additional steps relating to the recovery, conversion or reuse of carbonate or bicarbonate by-products according to the '093 application.

The hydrogen production reaction of the present invention can also be carried out in the presence of a catalyst such as carbon, carbon black, graphite, a transition metal or a transition metal complex. Non-homogeneous or homogeneous catalysts are also within the scope of the invention.

The above discussion and description are not meant to be limiting of the invention, but are merely illustrative. It will be apparent to those skilled in the art that there are many equivalents of the specific embodiments disclosed herein. The scope of the present invention is defined by the following claims, including all equivalents and modifications thereof.

Figure 1. Cumulative volume (cubic centimeters) of hydrogen produced by the reaction of ethylene glycol with a base as a function of reaction time.

Figure 2. Cumulative volume (cubic centimeters) of hydrogen produced by the reaction of ethylene glycol with a base as a function of reaction time.

Claims (14)

A method for producing hydrogen, comprising the steps of reacting an acyclic organic substance having a polyol function with a base to form the hydrogen; wherein the organic substance is a glycol or a triol; the base is a metal a hydroxide compound; and the reaction step further forms a salt of an organic acid. The method of claim 1, wherein the organic substance is ethylene glycol. The method of claim 1, wherein the organic substance is glycerin. The method of claim 1, wherein the reaction between the organic substance and the base is carried out in a liquid phase. The method of claim 1, wherein the reaction between the organic substance and the base is carried out between a vapor phase organic substance and a solid phase base. The method of claim 1, wherein the organic substance and the base are carried out in the presence of water. The method of claim 1, wherein the metal hydroxide compound is an alkaline earth metal hydroxide compound. The method of claim 1, wherein the reacting step is carried out at a temperature lower than a boiling point of the organic substance. The method of claim 1, wherein the reacting step further forms a salt of an organic substance in an oxidized form. The method of claim 9, wherein the salt is an organic acid Salt. The method of claim 1, wherein the reacting step further forms a carbonate or bicarbonate compound. The method of claim 11, further comprising the step of reacting the carbonate or bicarbonate compound with a metal hydroxide. The method of claim 11, further comprising the step of thermally decomposing the carbonate or bicarbonate compound, the thermal decomposition step of producing a metal oxide. The method of claim 1, wherein the reacting step comprises an electrochemical reaction carried out in an electrochemical cell, wherein the organic substance, the base and the electrolyte are placed in the electrochemical cell, To form an electrochemical reaction system comprising an anode and a cathode in contact with the electrochemical system, the electrochemical reaction being initiated when a voltage is applied between the anode and the cathode.